A) Field of the Invention
The present invention relates to a probe unit for inspecting an electrical property of electronic devices such as a semiconductor integrated circuit and a liquid crystal panel and manufacturing methods of the probe unit.
B) Description of the Related Art
Conventionally, a probe unit having a probe that contacts with electrodes of a sample and projects tip parts of a large number of leads aligned in a parallel configuration from a substrate is well known. In a probe unit disclosed by Japanese Laid-Open Patent 2002-286755, since microscopic probes project from a substrate, the probe unit can be overdriven without adding large power on the sample, and a plurality of probes can securely be contacted with a plurality of electrodes of the sample at the same time.
On the other hand, in an inspection of the liquid crystal panel for a display device, a reliable inspection result may be obtained by making a contact pressure between electrodes of a sample and the probes large enough. Japanese Laid-Open Patent 7-211752 discloses contact parts as probes does not project from the substrate, a probe unit that can enlarge a contact pressure between electrodes of the sample and the contact parts by using elasticity of a flexible substrate.
However, since slits corresponding to a pitch of the contact parts are formed at the edge of a substrate holding the contact parts in the probe unit disclosed in the Japanese Laid-Open Patent 7-211752, each contact part can be modified independently. Therefore, when each contact part greatly deforms with the substrate being strongly pressed by a bump of electrodes, adjacent contact parts may contact each another. Also, when a width of each edge part of the substrates divided by slits becomes small to the thickness of the substrates, possibility of contacting adjacent contact parts each another may be large because each edge part tends to deform to the width direction.
Also, in the probe unit disclosed in the Japanese Laid-Open Patent 7-211752, the contact parts contacting the electrodes of the substrate and the electro conductive film having the leads and the electrodes are formed along with the edge of the substrate extending to the reverse side. The leads and the contact parts extending to the reverse side are formed with pouched plating covering the tips divided by the slit formed on the edge of the substrate. Because the contact parts and the leads are not formed on the same surface, it will be impossible to conduct the electrodes of the sample and the leads of the probe unit when the contact parts are worn down. Further, because the contact parts of the probe unit are formed on the reverse side of the surface where the leads of the substrate are formed, the leads may be peeled off from the substrate when the substrate are bent by a strong force is impressed on the contact parts.